It's also because, until Apple's C-series models, they would've had to use Qualcomm modems which had a percentage-based royalty, and Apple would likely need a new contract for usage in Macs, so may had to pay even more. Even with their own modems they still have to pay Qualcomm's patent royalties, so it's likely just don't want to do that on devices which can cost over $10k today.

I don't want a seperate cable, and my iphone burn through battery like nothing when hotspoting.